1. Technical Field
The present invention relates to a method of manufacturing a semiconductor device which has a procedure of selectively removing a film to be etched by wet etching.
2. Related Art
In a semiconductor device, a terminal for external connection, such as a bump, is formed in order to mount the semiconductor device at the surface of a mounting board. In recent years, the terminal for external connection has been formed by forming a core with resin and selectively forming a conductive film over the core. Wet etching is used in the procedure of selectively forming the conductive film over the core.
Moreover, Japanese Unexamined patent publication No. 2003-151949 discloses that the top surface of a wafer faces downward in a chemical processing apparatus used in a lift-off method. An object of the technique described in Japanese Unexamined patent publication No. 2003-151949 is to prevent a metal located at a surface of a resist from coming in contact with an interconnect pattern when the resist is lifted off. That is, if the top surface of a wafer faces downward in lift-off, an unnecessary metal which began to be lifted off from the wafer hangs downward due to its own weight. Accordingly, the unnecessary metal is prevented from coming in contact with an interconnect pattern.
In addition, Japanese Unexamined patent publication No. 2005-281720 discloses that a plating solution is circulated by collecting the plating solution from the bottom surface of a plating bath and then supplying it from the upper side of the plating bath in an electrolytic plating processing apparatus.
In wet etching, the concentration of etchant may not be uniform at the surface to be etched which is formed with a layer to be etched. In this case, the etching rate may not be uniform at the surface to be etched. The inventor has found out that one of the causes is a reaction product generated at the time of etching. That is, although a reaction product is generated at a layer to be etched, the reaction product drifts near the surface to be etched after being generated. Accordingly, the reaction product inhibits the etchant, which has not reacted yet, from approaching the surface to be etched. For this reason, it is desirable to make the reaction product, which is generated at the time of etching, move quickly away from the surface to be etched.